The human eye is a very complex organ comprising numerous interacting elements which gather, focus, and transmit light rays to nerve endings which eventually transmit the information to the brain for image perception. The eye includes a natural crystalline lens of avascular tissue, the transparency of which depends upon the critical regularity of its fibers and the balance of its chemical constituents. Obviously, there are enumerable factors which may interfere with lens makeup and thereby affect its transparent character. No matter what the reason, a condition of opacity in the lens, commonly called cataract, reduces the visual performance of the eye. When the visual performance is reduced to an unacceptable level, surgical cataract extraction becomes a necessity.
An eye without a lens, a condition called aphakia, is obviously defective from an optical point of view in as much as it cannot properly refract incident light rays. Aphakic correction may be accomplished in three ways:
(1) thick eye glasses worn in front of the eye; PA1 (2) contact lenses worn on the eye, or PA1 (3) artificial intraocular lens implant within the eye.
It is this latter procedure with which the instant invention is concerned.
The structure and procedure of installing an intraocular lens is very critical because of the elements which make up the eye are extremely sensitive and subject to irreparable damage. Numerous experimental lens designs have been abandoned through the years because they caused corneal damage and other manifestations of intraocular irritation. For example, in the late 1940's and early 1950's, H. Ridley conducted clinical experiments with an artificial intraocular lens which included a lens portion having foot-like projections extending radially away therefrom. This device was placed in the posterior chamber with the feet extending between the ciliary processes and the base of the iris. The lens proved positionally unstable and resulted in unsatisfactory amounts of irritation.
Many attempts have been made to provide a satisfactory intraocular lens. In an effort to remedy the problems associated with the prior art lens implants, applicant previously has been granted U.S. Pat. Nos. 4,143,427; 4,166,293; 4,251,887 and 4,575,374.
In the co-pending application, three different lens configurations were described. The instant invention involves a further development of the lens of the co-pending application.
Therefore, it is a principal object of this invention to provide an improved posterior chamber lens.
A further object of the invention is to provide a posterior chamber lens wherein a ring-shaped member extends around a centrally positioned lens body with connecting members extending between the lens body and the fixation member.
Yet another object of the invention is to provide a lens of the type described which is of one-piece construction.
Still another object of the invention is to provide a lens of the type described including a ring-shaped position fixation member which may be compressed relative to the centrally positioned lens body to enable the implant to be inserted into the capsular bag.
Still another object of the invention is to provide a posterior chamber lens which will remain in place even if pressure or force is inadvertently applied to one portion of the lens.
These and other objects will be apparent to those skilled in the art.